Study of the changes in i.r. spectra bands of coal after reductive alkylation

Depolymerization reactions of a Spanish bituminous coal, such as reductive hydrolysis and alkylation, and O-alkylation, were investigated by Fourier transform infrared spectroscopy (FT-i.r.). The spectra show that the reductive hydrolysis increases the phenolic hydroxyl groups, whereas these decrease by alkylation. These changes in the OH group content were studied in relation to variations in the absorbances at 3800–2000, 1700, 1600 and 1112 cm⁻¹, and some linear correlations were found, which seem to indicate a clear contribution of the OH groups to the intensity of the broad band near 1600 cm⁻¹. The influence of the phenolic OH groups on the C=O vibration frequency at 1700 cm⁻¹ was also studied.     

Chemistry and structure of coals: Diffuse reflectance i.r. spectroscopy equipment and techniques

Diffuse reflectance infrared spectroscopy (DRIS) is used to obtain high quality data on the chemistry and structure of coals and related materials. Minimum sample preparation is required to form a diffusely reflecting surface thus saving time and minimizing structural and chemical modifications. Controlled environment chambers are used to study atmospheric effects and/or in-situ reactions (hydration/dehydration, oxidation/ reduction, derivatization, etc.) of coals and inherent, secondary and/or added minerals. Quantitative measurements of the mineral content may be made either by measured addition or by weighted spectral subtraction. Detailed study of in-situ oxidation gives the concentration of the intermediate transient states of hydrocarbon loss. The progressive insertion of oxygen into aromatic rings to give steady state levels of slow char burning can also be revealed. DRIS is a simple, fast, versatile and informative method for coal analysis.     

煤化学结构模型研究进展及应用

为了解煤结构与反应性之间的关系,论述了褐煤、次烟煤、烟煤、无烟煤的典型化学结构模型,分析了煤的化学结构模型在煤热解、煤气化、煤液化、煤自燃及煤的溶剂溶胀性中的应用。煤的化学结构模型有助于在分子水平上研究煤反应过程中的反应路径和反应机理。煤结构模拟的方法能够有效捕获煤热解过程中化学键的生成和断裂行为,解释煤气化反应机理,有效检测或捕获煤液化时生成的不稳定自由基,从微观方面分析影响煤自燃的因素,达到预防煤炭自燃的目的。     

Fourier transform infrared photoacoustic spectroscopy of raw coal

Photoacoustic Fourier transform infrared (PA-FT-i.r.) spectrometry was employed to examine raw coal containing 13–64 wt%, daf volatile matter (VM). Sample preparation for i.r. examination was the same as for ASTM proximate analysis. Technological and spectroscopic information on representative samples were obtained. PA scan time is longer than for conventional FT-i.r. operation; however sample preparation is faster and easier. The time-consuming KBr pellet technique, possibly affecting coal structure, is avoided. The i.r. absorption in the OH, NH, CH_ar and CH_x,al regions may allow the determination of VM for both high- and low-rank coal. Some differences between present PA and diffuse reflectance spectra of raw coal from the literature are discussed.     

气化剂预热温度对加压湍动循环流化床煤气化的影响

在实验室规模加压湍动循环流化床气化炉上,研究了气化剂预热温度对煤气化特性的影响。结果表明：气化介质温度从400℃提高到700℃后,煤气热值增加21%;煤气中可燃组分H₂和CO浓度分别从10.55%和9.57%提高到13.62%和13.12%;不可燃组分N₂和CO₂浓度分别从61.03%和16.14%降低到57.03% 和13.7%;甲烷含量变化较小;冷煤气效率由49.3%增加到56%。碳转化率和干煤气产率随气化剂预热温度的不同变化较小。实现了循环流化床提升段下部湍动流化、上部环核流动的特殊流场结构,与已有研究结果相比,煤气热值、煤气产率、冷煤气效率都略有提高,更加适合煤气化。     

New chemical structural features of coal. The structure of coal products

The object of this paper is to demonstrate the usefulness of the transalkylation reaction for determining chemical structural features of products derived from coal. For example, the method is applied to derivatized coals, coals modified by thermolysis, and materials physically or chemically separated from coals. Data are presented for the pyridine soluble and insoluble parts of two coals, an O-methylated coal, a Birch reduced coal, a solvent refined coal, and a coke. Similarities and differences in chemical make-up of these materials are discussed.     

New chemical structural features of coal. A comparison of several coals

Structural features of several coals of different ranks are compared using an adaptation of the transalkylation reaction. In the present application of this method, trifluoromethanesulphonic acid is used as catalyst and toluene is used in excess as acceptor and solvent. The process can be visualized as a disproportionation reaction in which intermolecular alkyl transfers occur. Under the influence of the acid catalyst, aryl-alkyl bonds in coal are cleaved and alkyl-aryl bonds are formed with the excess toluene solvent. Thus, a large number of substituted toluene derivatives are formed by transfer of groups from coal. Concentrations of ≈ 20 substituent groups and connecting groups are estimated and compared for a range of coals and numerous other compounds are present in small amounts. These compounds are tabulated for two coals and the possible significance and origin of some of them are discussed. The mechanism of the transalkylation reaction as it applies to coal and the reactions of a limited number of relevant model systems are also discussed.     

Relation of the chemical structure of coal to its hydropyrolysis

The hydropyrolysis of Illinois No. 6 coal has been studied in a batch reactor, in which the reactions were initiated by explosion of $\text{H}{}_2\text{O}{}_2$ mixtures. The ratio of H₂ to O₂ was kept at 8, while the total pressure of the gas mixture was changed to vary the reaction temperature. The heating rate was ≈ 50 000 °C s^?1, and the reaction time was < 50 ms. The conversion of the feed coal increased from 19% at 620 °C to 81%at ? 1500 °C. At conversions < 50%, the gaseous product consisted of mainly CH₄ and CO in almost equal proportions, and at conversions ? 60% the concentration of CO increased. Comparison with results from a large flow reactor revealed that comparable conversions were obtained in the present batch reactor, although product distributions were markedly different from each other. The dissimilar product distribution is attributed to different reacting media: preburning of H₂ and O₂ in the flow reactor versus in situ burning of the mixture in the batch reactor. The H/C ratios of solid residues after the hydropyrolysis decreased linearly as the conversion increased, revealing that the portions of coal having high H/C ratios were preferentially gasified. This observation was substantiated by a high H/C ratio, 1.74 of the first portion of coal gasified, and by a sharp decrease in H/C ratio in subsequent gasified portions. These data indicated that aliphatic side chains (or linkages) and single-ring aromatic clusters in the feed coal were gasified first, followed by larger aromatic clusters. Semi-quantitative determination of the distribution of different aromatic clusters showed good agreement with current structural information on coal. Thus, the effects of reaction variables were explained in terms of the structural features of coal, and the ratelimiting steps in the hydropyrolysis process were identified.     

溶胀处理煤对煤结构与煤基聚苯胺导电性影响

首次选用苯胺为溶剂对神府煤(SFC)进行溶胀处理,以研究其对煤结构与煤基聚苯胺导电性的影响,对其结构进行TG/DSC、FTIR和SEM分析,并通过溶胀SFC处理煤为聚合基体,在苯胺和引发剂条件下聚合为煤基聚苯胺,测定了其导电率。结果表明:苯胺溶胀处理破坏了煤中非共价键,降低了煤的交联缔合度,疏松了煤的孔结构,在此条件下的煤基聚苯胺的导电率均小于溶胀处理前原煤为聚合基体的煤基聚苯胺导电率,这与煤大分子网络结构受到一定程度破坏有关,这可为煤基聚苯胺的扩大化生产提供重要参考。     

Effect of temperature,catalyst and charge gas on the mean chemical structures of the products from hydrogenation of Liddell coal

Liddell coal (New South Wales, Australia) has been hydrogenated at 400, 425 and 450 °C with excess tetralin as vehicle and nitrogen or hydrogen as charge gas for 4 h at reaction temperature. In some experiments a nickel-molybdenum catalyst was used. The structures of the liquid and solid products were investigated by nuclear magnetic resonance spectroscopy, gel permeation chromatography and combustion analysis. Increasing the hydrogenation temperature from 400 to 450 °C decreases the yield of liquid products but increases conversion. At higher temperatures the liquid products are smaller in molecular size and molecular weight and contain a greater proportion of aromatic carbon and hydrogen; the solid residues also contain a greater proportion of aromatic carbon. The changes in variation of yield and structure with temperature are independent of the presence of catalyst under nitrogen and the nature of the charge gas. However, as the reaction system is capable of absorbing more hydrogen than can be supplied by the tetralin, the products from reactions with hydrogen as charge gas contain more hydrogen, some in hydroaromatic groups. Catalyst has little, if any, role in dissolution of the coal when a nitrogen atmosphere is used. When nitrogen is used as charge gas, reactions of coal-derived liquids with the catalyst do not alter the hydrogen, carbon or molecular size distributions in the products. The results show that the changes in composition of the liquid and solid products with increase in hydrogenation temperature are due to pyrolytic reactions and not to increased hydrogenation of aromatic rings.     

六盘水矿区煤炭及煤化工产业发展的思考

本文分析了造成六盘水矿区煤炭及煤化工产业不景气的原因,并就如何促进该地区煤炭及煤化工产业的发展给出了一些建议。     

煤化工与盐化工联合发展的循环经济之路

阐述了煤化工与盐化工联合发展走循环经济发展之路的产业背景,提出通过煤盐化工联合,可大力发展精细化工产品,延长产品链,实现结构调整与产业升级,提高企业的经济效益。     

浅谈煤化工发展趋势

本文介绍了国内外煤化工发展现状,根据国家发展规划对煤化工项目从市场和技术方面进行分析,提出煤化工项目未来的发展方向.     

煤化工取样系统设计实例

简述化工装置取样系统的设计原则,结合具体的工程设计实例,列举了煤化工各装置中取样形式,并阐述了各种取样形式在设计过程及取样过程中需要注意的问题。     

新型煤化工技术和经济竞争力分析

对煤化工及新型煤化工产业的分类和主要技术进行了归纳,分析和对比了新型煤化工各产业的竞争力,为计划投资新型煤化工项目建设的企业提供一定的借鉴。     

Regular coal structure and conversion severity

In two separate coal conversion studies, one dealing with CO-water conversions of Illinois No. 6 coal, and the other with H₂S addition to conventional tetralin conversions of the lower-rank Wyodak 2, data have been collected over a range of conversion levels. For both studies the degrees of conversion were increased by increasing the reducing power of the medium, while the conversion temperature was kept constant at 400 °C for all runs. The conversion levels for the CO-water runs ranged from 29 to 60%, while the tetralin-H₂S runs yielded conversions from 44 to 67%. Sequential elution solvent chromatography and field ionization mass spectrometry were used for analyses of toluene-soluble fractions from the CO-water runs and THF-soluble fractions from the H₂S-tetralin runs, respectively. The analyses showed that the fraction compositions remained constant with increasing degrees of conversion. This finding suggests that there may be some gross regularity in the structure of coal. Moreover, the results here are in contrast to work reported earlier, in which increased conversion levels, reached through greater conversion temperatures, yielded products with successively increased condensation and aromatization. It is thus suggested that severity be considered in terms of two components. Thermal severity reflects the temperature/time component of conversion chemistry, and derives from simple Arrhenius behaviour of competing reactions, while reduction severity reflects only on the reducing power of the system.     

煤化工废水零排放技术探析

煤化工企业作为污染物排放产业,尤其是废水的排放,会对水体造成严重的污染。所以,如何才能够使煤化工企业废水的零排放,就成为当前重点研究的课题。在阐述煤化工废水零排放技术的基础上,通过实例分析,希望可以找出可行的方案。     

Liquefaction reaction of coal: 2. Structural correlation between coal and its liquefaction products

The structural correlation between coal and its liquefaction products has been examined using cross-polarization, magic angle spinning (CP/MAS) ¹³C n.m.r. and field ionization mass spectrometry (f.i.m.s.). The CH₂/aromatic carbon ratios of all solid products (asphaltene, preasphaltene and residue) were close to the corrected +CH₂/aromatic carbon ratio for the coal. This suggests that the ring structure of the structural unit of each solid product is essentially similar to that of the parent coal, except for a difference in the degree of polymerization of the structural units. The CH₂/aromatic carbon ratios of aromatic ring-type oil fractions also correlated with the corrected ratio for the coal, although they were larger. The z series distribution obtained from the f.i.m.s. of oil fractions revealed that coal with a higher CH₂/aromatic carbon ratio produced an oil rich in naphthenic structures.     

Solid state magnetic resonance spectra of Illinois No. 6 coal and some reductive alkylation products

Illinois No. 6 coal and its reductive methylation and butylation products have been studied by magnetic resonance techniques. Conventional CP-MAS¹³Cn.m.r. spectroscopy indicates that 62% of the carbon atoms in the coal are aromatic and that about 6% of the carbon atoms are carbonyl. Esters are more abundant than carboxylic acids. The resonances of methoxy groups and other novel etheric carbon atoms are apparent in the high field region. Dipolar dephasing experiments suggest that methyl carbon atoms constitute no more than 16% of the carbon, methylene and methine carbon atoms about 14% and quaternary aliphatic carbon atoms about 2%. The dipolar dephasing experiments in conjunction with previous work also permit estimates of the hydrogen atom distribution. The THF-insoluble products obtained in the reductive alkylation reactions with¹³C-enriched alkylating agents contain paramagnetic and ferromagnetic substances that adversely influence the solid state n.m.r. spectra. However, good ¹³C n.m.r. spectra were obtained after these substances were extracted with aqueous hydrochloric acid. The O:C alkylation ratios are 1.2 and 1.0 for methylation and butylation, respectively. Dipolar dephasing experiments establish that the decay constants of functional groups in the whole coal and of C- and O-methyl-¹³C and C- and O-butyl-1 -¹³C nuclei in the labelled coal molecules are very similar to those of reference compounds. These findings suggest that the decay constants measured for the ¹³C nuclei in coals and coal-derived solids provide reliable information about their degree of substitution.     

Studies related to the structure and reactivity of coals 17. The chemical structure of asphaltenes and residues from reactions of Victorian brown coals

The chemical structures of the asphaltenes and residues from reactions of a range of brown coals with widely varying atomic H/C ratios have been examined by chemical and spectroscopic methods, and have been shown to be remarkably consistent. Asphaltenes and residues from brown coals with high atomic H/C ratios show a small but significant increase in incorporation of aliphatic, guest material although the main bulk of material is derived from the host component of the coal (i.e. ligno-cellulosic or tannin derived material).